Small walk behind mowers and large riding mowers have long been known to the industry. Mid-size riding mowers have also been introduced for high speed mowing on relatively unobstructed lawns. A need has been recognized also for a mid-size walk behind mower. "Mid-size" is generally recognized to encompass mowers in the range of approximately 36-60 inches. Even though these mowers cut a swath the same width as a comparable riding mower, they are slower, and thus more maneuverable. The walk behind mowers are usually utilized on large lawns with numerous trees, shrubs, flowerbeds and the like which necessitate intricate trimming and interfere with the high speed operation of the riding mowers. Walk behind mowers are also often used in areas with steep slopes, which may pose traction of tipping problems to riding mowers. Walk behind mowers are also generally considerably less expensive than riding mowers.
The typical prior art mower of this type has two handles equipped with squeeze-type levers controlling two driving wheels mounted at the rear corners of the cutting unit. When the mower is shifted into a driving gear, it will proceed in the selected direction. To make a turn, one of these squeeze-type levers must be pressed to either engage a brake or to overcome a spring loaded idler, thus removing tension from a drive belt and disengaging the drive to that wheel. The other wheel continues to drive, thus effecting the turn. This type of control could be characterized as "normally engaged", since it is engaged unless shifted out of gear, or both levers pressed simultaneously. If the operator slips and falls, or otherwise unintentionally leaves the operator's position, the unit will proceed in the selected direction until it is stopped by an obstruction or other means.
Because a tension spring biasing an idler pulley against a drive belt is normally quite strong to prevent belt slippage, it takes considerable force to squeeze the levers to disengage the drive. Engaging a brake with a hand lever can also require a considerable amount of effort. When cutting a lawn with many trees, shrubs, and the like which necessitates a great amount of turning, the operator's hands, wrists and arms are subject to significant fatigue. There are various other disadvantages to machines of this general type. For example, it is necessary on many models to lock out both hand levers with thumb screws or other means in a specific position to place the drive in neutral in order to start the engine. Then the levers must be unlocked before the machine can be put in motion.
The present invention overcomes the problems and disadvantages of the prior art, and discloses a novel control system that provides simplified means for controlling the functions of a walk behind mower or the like.